Infection with the human immunodeficiency virus (HIV) (formerly HTLV-III/LAV) is transmitted by sexual contact, by blood and blood products, and perinatally. There is no evidence for casual transmission. The risk to health care workers is low but appropriate infection control precautions should be taken. Specimens should be transported to the laboratory in plastic bags labeled with an easily recognized biohazard warning. Placing patients in private rooms is unnecessary unless a patient has an additional illness that requires such an arrangement. Disinfection, sterilization, housekeeping, and waste management must be done according to recommended guidelines. Asymptomatic hospital personnel with HIV antibody can safely engage in direct patient care. Routine HIV serologic screening of personnel or patients is not recommended. Counseling and HIV antibody testing should be offered to pregnant high-risk women. Laboratories that process specimens potentially containing HIV virus should adhere to maximum containment procedures. An intensive and continuing educational program on the epidemiology of HIV infection and appropriate infection control practice is recommended.